Consistent Thermodynamic Dataset Research Articles

Germanium‐Iodine System, Thermodynamic Study assessment and complementary experiments

AbstractLiterature thermodynamic data (enthalpies, entropies, and heat capacities) of the condensed species GeI4(s)(I) and GeI2(s) are revised.Entropies and heat capacities of the gaseous species GeI4(g), GeI2(g), and GeI(g) are calculated by the R.R.H.O. method. Published experimental investigations of the equilibria: GeI4(l) ⇌ GeI4(g), GeI4(s) ⇌ GeI4(g), 2 GeI2 ⇌ Ge(s) + GeI4(g), GeI4 ⇌ GeI2(g) + I2(g), GeI2(s) ⇌ GeI2(g) and Ge(s) + GeI4(g) ⇌ 2 GeI2(g) are discussed. In addition, new measurements of the total pressure above the saturation ranges of the GeI4(l) and for the reaction: Ge(s) + GeI4(l) ⇌ 2 GeI2(g) are performed.Enthalpies of formation of GeI4(g) and GeI(g) are deduced. Enthalpy of formation of GeI(g) is estimated from the evolution of the dissociation energy D°(GeX) (X = Cl, Br, I) against the Z atomic number and from the spectroscopic constants of this molecule. In conclusion a self consistent set of thermodynamic data concerning the germanium‐iodine system is proposed.

An internally consistent thermodynamic dataset with uncertainties and correlations: 2. Data and results

Abstract This, the second of two papers, represents the application of a least squares approach, discussed in the previous paper, to the generation of an internally consistent thermodynamic dataset involving 60 reactions among 43 phases, in the system K2O–Na2O–CaO–MgO–Al2O3–SiO2–H2O–CO2. We make the assumption that all the thermodynamic data, with the exception of enthalpies of formation of the phases, are well known, and solve for an internally consistent set of enthalpies which reproduces the 60, experimentally determined, phase equilibrium reactions. An important difference between our dataset and that of previous alternatives in the literature is that we are able to determine the uncertainties on, and correlations between, the enthalpies of formation for all phases in the set, and hence are able to apply simple error propagation techniques to determine the uncertainties in any phase equilibrium calculations performed using this dataset. Selection of reactions, for geothermometry and geobarometry, may be more readily made by choosing equilibria with small uncertainties in their thermodynamics. Our data are in reasonably close agreement with the high temperature molten oxide calorimetry results on silicate minerals where available, a fact which lends a degree of confidence to the results.

An internally consistent thermodynamic dataset with uncertainties and correlations: 1. Methods and a worked example

Abstract This, the first two papers, sets out the philosophy and methods of determining an internally consistent thermodynamic dataset for minerals using the least squares method. The applicability of the least squares method is discussed, and it is applied to a small set of experimental equilibria in the system Na2O–Al2O3–SiO2–H2O. The importance is stressed of defining not only the enthalpies of formation of minerals, but also the uncertainties and the correlations among them. The system which has been used as an illustration for this paper serves as a visual guide to the method, as it is small enough to represent graphically in two dimensions. In the paper which follows, we extend the method to a system of 60 equations (experimentally determined equilibria) involving 34 unknowns (enthalpies of formation of mineral end‐members).

ChemInform Abstract: A MASS SPECTROMETRIC INVESTIGATION OF IRON(II) IODIDE

AbstractDie thermodynamische Analyse des Felz‐Systems umfaßt Knudsen‐Zellen‐Messungen mit Partialdruckbestimmungen in der Gleichgewichts‐Gasphase und Ableitung von Sublimations‐, Bildungs‐ und Dimerisationswärmen sowie Bindungsenergien.

An internally consistent set of thermodynamic data for twentyone CaO-Al2O3-SiO2- H2O phases by linear parametric programming

The technique of linear parametric programming has been applied to derive sets of internally consistent thermodynamic data for 21 condensed phases of the quaternary system CaO-Al2O3-SiO2-H2O (CASH) (Table 4). This was achieved by simultaneously processing: a) calorimetric data for 16 of these phases (Table 1), and b) experimental phase equilibria reversal brackets for 27 reactions (Table 3) involving these phases.

A Mass Spectrometric Investigation of Iron(II)‐Iodide

AbstractA consistent set of thermodynamic data for solid FeI2 and for molecules which constitute its equilibrium gas phase is provided, based on measurements by the high‐temperature mass spectrometry and electron impact techniques. Second‐ and third‐law heats of formation, atomization and reaction, as well as individual Fe‐I bond strengths, are reported for the species FeI2(g), Fe2I4(g), Fe2I2(g) and for solid FeI2. Partial and total pressure data are also given, as well as an up to date literature survey of thermochemical data for the FeI2 system.

A thermodynamic analysis of the Cu-O system with an associated solution model

An extension of the associated solution model is developed and applied to the Cu-O liquid phase. Associated species “Cu2O” in the liquid solution are assumed, which interact with the surrounding free Cu and O atoms. All thermodynamic properties and the phase diagram calculated from this model are in good agreement with the experimental information. The success of this mathematical description is, of course, no proof for the physical existence of associated species. A consistent set of thermodynamic data of the various solid, liquid, and gaseous phases is given by this comprehensive evaluation. In addition, linear approximations for the Gibbs energies of reaction of formation and the interaction coefficients are offered. A metastable liquidus of the compound CuO at elevated pressure is predicted, the congruent melting point being 1228 °C at δC atP O 2 = 24.4 atm (2.47 MPa).

Thermodynamic properties of quartz, cristobalite and amorphous SiO 2: drop calorimetry measurements between 1000 and 1800 K and a review from 0 to 2000 K

We report relative enthalpy measurements on quartz, cristobalite and amorphous SiO 2 between 1000 and 1800 K. We have observed a glass transition around 1480 K for amorphous SiO 2. From our results and available C p, relative enthalpy, and enthalpy of solution data we have derived a consistent set of thermodynamic data for these phases. Our calculated enthalpies of fusion are 8.9 ± 1.0 kJ mole −1 for cristobalite at 1999 K and 9.4 ± 1.0 kJ mole −1 at 1700 K for quartz.

Gibbs energies of formation of Mn 3C, M(Fe, Mn) 3C and Mn 23C 6 from the ternary phase equilibria in the FeMnC system

The high temperature phase relations in the FeMnC system have been analyzed in light of the recently developed thermodynamic method by the authors to obtain the Gibbs energies of formation of Mn 23C 6 and Mn,C. A new thermodyn/amic treatment is outlined and applied to obtain the stability of the ternary carbide M(Fe,Mn) 3C without any a priori assumption of a solution model for the M 3C phase. The recommended Gibbs energies of formation for the Mn carbides, Mn 3C and Mn 23C 6 With γ-Mn (graphite) as the Standard states are: Δ G 0 Mn 3 C =−16.9−0.015 T kJ 1243≤ T≤1323 K Δ G 0 Mn 23 C 6 =−133.7−0.090 T kJ 873≤ T≤1273 K The present method can be extended to obtain a consistent set of thermodynamic data for binary and ternary carbides from various ternary metal-metal-carbon phase relations.

Thermodynamische Untersuchungen im System Gold?Cadmium, 2. Mitt.

Liquidus and solidus curves of the β-AuCd phase were determined byDTA measurements. β-AuCd has a congruent melting point of 629.5°C at 47 at% Cd with no signs of other minima or maxima in the liquidus curve between 43 and 51 at% Cd. Liquid and solid Au−Cd alloys were investigated by theemf method between 40 and 90 at% Cd and 653–973 K. A consistent set of integral thermodynamic data for liquid and for solid alloys of the entire Au−Cd system were calculated at 1000 and at 700K, resp., using values taken from the literature. Partial molar entropies of Cd of solid β-AuCd and of liquid alloys in the same concentration range were compared and discussed with respect to ordering phenomena in solid and liquid alloys.